Modern particulate detergent composition contain a wide variety of ingredients. At the same time the consumer requires a particulate detergent composition which has acceptable physical characteristics such as, for example, being flowable and pourable in the case of powders and having good dispensing and dissolution properties in the case of tablets. The physical properties must remain acceptable even after storage for a number of weeks in the supply chain.
Many ingredients which provide a useful benefit to the detergent composition are difficult to include because they are liquid. However, liquid ingredients are not in themselves a problem as long as sufficient liquid carrying capacity is present in the solid portion of the detergent. Of more difficulty are the ingredients which are hygroscopic, which may be either liquid or solid. Hygroscopic materials are difficult to handle since they absorb atmospheric moisture over time during storage and can lead to a deleterious effect on physical properties such as undesired caking and subsequent reduction in flowability at the point of use or a reduction is dispensability, dispersability or dissolution rate.
U.S. Pat. No. 4,196,095 (Church & Dwight) discloses a carbonate based detergent composition which comprises magnesium stearate in order to reduce insoluble lump formation in cold water.
U.S. Pat. No. 2,589,330 (Swift & Co) discloses a cleansing composition comprising trisodium phosphate and silica. A magnesium compound is added to prevent caking.
The present inventors have found that specific carboxylic acid salts are especially effective at reducing the negative effects on physical properties of particulate detergent compositions or components therefor due to moisture uptake.
Thus, the present invention provides a free-flowing particulate detergent composition or component therefor which comprises a bi- or tri-valent metal ion carboxylic acid salt which, without the salt being present, has a hygroscopicity value of greater than 25%.